Last week I got that message on my Computer. After trying to unlock the computer I called the so called Microsoft number they tell you to call. I kind of got suspicious as soon as they answered the phone sounded like a chinese girl. After trying this and that she finally got her supervisor on the phone. He tried a few things and said I can't help you from here but I can tell you how to fix it offline. He told me I had to go to a CVS or Walgreens and purchase $500 worth of gift cards. He told me to get dressed and go now and he would hold on the phone at that point I hung up the phone. The computer was still screwed up repeating about the warning. Tonight I got the same message when I clicked on something on the Fox website. I couldn't remember how I got it working again the last time so I finally restarted the computer and that cleared it. I did a check for security and updates and there were a few dealing with malicious websites. So I downloaded them rechecked the computer and it's been fine.
